Diamond stylus for disc records

ABSTRACT

A pressure scanning diamond stylus having an elongated lower edge in a wear resistant crystallographic orientation.

United States Patent [1 91 Batsch et a1.

[ 3,781,020 [451 Dec. 25, 1973 DIAMOND STYLUS FOR DISC RECORDS [75]Inventors: Helmut Batsch; Benno Jahnel, both of Berlin; Ernst AugustWeinz, Idaroberstein; Wolfgang Berger; Gerhard Dickopp, both of Berlin,all of Germany [73] Assignee: Licentia Patent-Verwa1tungs-G.m.b.1-I.,Frankfort am Main, Germany 22 Filed: Nov. 29, 1971 211' Appl. No.:202,988

[30] Foreign Application Priority Data Nov. 30, 1970 Germany P 20 60317.2

Nov. 30, 1970 Germany HGM 70 45 295.8

[52] US. Cl. 274/38 [51] Int. Cl. Gllb 3/44 [58] Field of Search 33/18R; 274/38; 125/39 [56] References Cited UNITED STATES PATENTS 3,138,8756/1964 Christensen 33/18 R 1,373,635 4/1921 Rammelsberg 274/38 FOREIGNPATENTS OR APPLICATIONS 599,964 7/1934 Germany 274/38 300,220 8/1917Germany 274/38 OTHER PUBLICATIONS Industrial Diamond Review. Vol. 20,Feb. 1960, Pages 31-37.

Primary Examiner-Harry N. Haroian Attorney-George H; Spencer et'al. I

571 ABSTRACT A pressure scanning diamond stylus having an elongatedlower edge in a wear resistantcrystallographic orientation.

15 Claims, 17 Drawing Figures FIG. 3 AMPLIFIER TRANSDUCER (5.0. PIEZOELECTR/C CERAMIC) 'lcn PICKUP CARTRIDGE CONTACTING POINT PATENIEU DEL 25m5 SHEET 2 OF 4 FIG. 4

Z F/G. 5C1

FATENTED DEC 2 5 1975 SHEET REF 4 DIAMOND STYLUS FOR DISC RECORDSBACKGROUND OF THE INVENTION A The present invention relates to diamondstyluses for guiding a pickup in the grooves of, for example, a discrecord and, optionally, also for sensing informationstoring, physicalundulations in the grooves. More particularly, the present inventionrelates to styluses for sensing a recording of a broad-band signalfrequency mix on a mechanical carrier, such styluses being of the typedisclosed in U. S. Pat. application Ser. No. 798,709 filed Feb. I2,1969, by Gerhard Dickopp et al., for a System for ReproducingMechanically Recorded Signals.

While it was previously only possible to sense physical undulations inthe grooves of a disc record up to a frequency of about 20,000 cyclespersecond, it has now become possible to sense undulations having afrequency of far greater magnitude, for example up to several megacyclesper second. The sensing able to detect these higher frequencies has beendisclosed in the above-mentioned application Ser. No. 798,709. Thestylus has an elongated lower edge and rides with pressure contact on aplurality of the physical protrusions of the undulations in a discrecord. The trailing portion of the elongated lower edge is abruptlyended by a substantially vertical stylus face and, as the elongatedlower edge suddenly loses contact with individual protrusions, thereoccurs an abrupt relieving of pressure on the stylus. This is registeredby an electromechanical transducer and appears as an electrical outputsig nal.

During pressure scanning of the above-described type, there is scarcelyany macroscopic movement of the pickup, since the pickup inertiaprevents it from macroscopically responding to the high frequencyundulations.

For recording and playing back signal oscillations in the megacycles/second range, the record carrier, for instance a disc record, mustmove at a high rotational velocity; for example for video signals a discrecord must move at 25 revolutions per second. It has been found thatdisc records themselves can withstand a high number of repetitions ofthe playback process without any reduction in 'quality. In contrast, thestylus, although made, for example, of diamond, eventually shows signsof wear and must be replaced.

It has been found in practice that, in spite of the use ofwear-resistant diamond material, pressure scanning styluses are worndown sometimes already after to hours of playing time.

SUMMARY OF THE INVENTION An object of the present invention, therefore,is to provide a pressure scanning diamond stylus of increasedwear-resistance.

This as well as other objects which will become apparent in thediscussion that follows are achieved, according to the presentinvention, by a pressurescanning diamond stylus having its elongatedlower edge in a wear-resistant crystallographic orientation.

GENERAL ASPECTS OF THE INVENTION In one embodiment of the invention, theelongated lower edge lies within about i 15 of a crystallographicoctahedral plane of the type (III) whose vector representation, i.e. the{111] vector, points downwards out of the diamond stylus as shown i nFIGS. 1 and 2, with the vector direction of the. type [1 l2] lyingwithin 1 15 of the direction of elongation of the lower edge andpointing from the leading portion of the lower edge toward the trailingportion (i.e. the [TT2] vector points in the same direction as thefriction force acting on the stylus when it is in contact with a discrecord).

Regarding the significance of the crystallographic planes anddirections, and their indices, reference is made to the bookAnorganische Chemie [Inorganic Chemistry] by Walter Hiickel, publishedby Verlag Akademische Verlagsgesellschaft, Leipzig C], 1950, pages 164and I65. Reference is also made to the book Elements of X-RayDiffraction by B. D. Cullity, published by Addision-Wesley, Reading,Massachusetts,

1956, pages 37 to 39 and 48 to 49; and to An Introduction toCrystaIChemistry by. R. C. Evans, published by Cambridge University Press,Cambridge, 1952, pages 28 and 29.

In a further embodiment of the present invention, the elongated loweredge lies in a crystallographic cubic plane of the type (100) with thevector direction of the type [011] lying in the direction of elongationof the lower edge, with tolerances of 15 likewise being comprehendedhere.

In another embodiment of the present invention, the elongated lower edgelies in a crystallographic dodecahedral plane of the type (110) with thevector direction of the type [T10] lying in the direction of elongationof the lower edge, with tolerances of t 15 likewise being comprehendedhere.

Since the elongated lower edge of the stylus of the invention generallyis often tilted upwards from the trailing portion to the leading portionat a small angle of 3 to 10 with respect to the center line of thegroove, it is preferred to set the direction of optimum abrasionresistance tilted oppositely at such an angle. This then assures duringuse that the preferred direction of the optimum abrasion resistance atleast approximately coincides with the direction of the relativevelocity or with the direction of the friction force exerted on thestylus.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view of apickup in contact with a disc record.

FIG. 2 is an elevational view of a modified pickup in contact with adisc record.

FIG. 3 is a left side view of the pickup of FIG. 2.

FIG. 4 is a perspective view of the unit cell of diamond.

FIGS. 5a to 5d are perspective views of different crystallographicplanes and directions in diamond.

FIGS. 6a and 6b, 7a and 7b, and 8a and 8b, are graphical representationsof wear in diamond.

FIGS. 9 to 11 are elevational views of diamond styluses according to theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 havebeen adapted from US. Pat. ap-

plication Ser. No. 142,237 filed May I l, 197], by Ger- I 3 cordedsignal. The pickup including the stylus is caused to bear with itselongated lower edge8 against the disc with a force sufficient toelastically deform the record disc, and to cause the undulation peaks tobe compressed beneath the stylus, in the manner illustrated in thedrawing. The direction of movement of the record disc 4 relative to thestylus 3 is shown by the arrow. The compression of the peaks is greaterat the trailing portion 9 of the edge 8 than at its leading portion 10.

The pickup includes a transducer body I, which is preferably apiezoelectric ceramic body, to which the playback stylus 3 of diamond isrigidly fastened by a glue or solder joint2. When the record disc iscaused to move relative to the stylus 3, the resultant reaction forceapplied by the elastically deformed disc to the stylus 3 is applied toceramic body 1 and converted by suitable circuitry connected to the bodyinto a corresponding output signal. This force alternates at a ratedetermined by the recorded wavelength and only its average value isdetermined by the bearing force with which the stylus is applied againstthe record disc.

FIG. 2 differs from FIG. 1 only in that the elongated lower edge is astraight line inclined 3 to from the undeflected plane of the record.

Stylus face 6 is substantially vertical and abruptly ends elongatedlower edge 8. It functions to create a sudden loss of contact betweenthe lower edge and an undulation peak.

FIG. 3 views FIGS. 1 and 2 from their left sides and shows that thecontacting point (the edge 8 appears as a point in FIG. 3) may actuallybe rounded off. FIG. 3 additionally shows leads bringing the voltagesappearing across the transducer to an amplifier; and-a pickup cartridge.

The stylus 3 of FIG. 2, if it is intended to serve for scanningfrequency modulated video signals, may have a length in the direction ofthe groove axis of approximately 0.2mm. Its bottom portion iswedge-shaped, as is evident from a comparison of FIG. 3. The edge 8 ofthe stylus is rounded as shown in FIG. 3 in a plane normal to the grooveaxis and has a radius of curvature of approximately 4p. in that plane.The face 6 has. a height of approximately 8011..

A spiral-shaped groove is disposed in the record surface and is formedso that its walls enclose an angle of approximately 140 normal to thegroove axis. The groove walls present the elastically depressablereliefshaped undulations which are shaped to constitute a spatialrepresentation of a frequency modulated oscillation. The wavelength ofthe cyclic undulation alternations varies between 2a and 5a. Thedifference in height between a peak and a valley of the undulations isapproximately la. 4 The rounded tracing edge of the wedge-shaped stylusslides upon the undulations of both groove walls and thus almostcompletely levels the undulations elastically. The stylus vertex,between the edge 8 and 6 in FIG. 2, has a radius of curvature ofapproximately 0.2;1. in a plane containing the groove axis.

The scanned signal has instantaneous frequencies between 2.75 Ml-Izand3.75 MHz, i.e., the frequency excursion of the scanned frequencymodulated oscillations is 1 MHz. Theceramic transducer body 1 effects aproportional conversion of the alternating force exertedon it into anelectrical voltage.

The structure of FIGS. land 2 may be incorporated with other discrecording structure, for example that disclosed in US. Pat. applicationSer. No. 154,545 filed June 18, 1971, by Eduard Schiiller et al. for aPositively Guided Disc Record Pickup.

Referring now to FIG. 4, there is shown the unit cell of diamond. Thecircles at the corners and faces of the cube, and at the certain it, A,A type locations within the cube, represent carbon atoms. The positionalrelationships of the carbon atoms relative to the axes X, Y, and Z arethe same in the remaining Figures.

In a diamond crystal, three distinct types of natural surfaces arefound:

I. the cubic planes of the type (100);

2. the dodecahedral planes of the type (110); and

3. the octahedral planes of the type (111).

In FIG. 50 these areas are shown for a crystal cube, reference being hadto FIG. 4 for the atom locations.

In FIGS. 5b, 5c and 5d, sections of FIG. 5a are shown to facilitateunderstanding of FIG. 5a.

FIG. 5b relates to the above-mentioned first embodiment of a stylusaccording to the present invention in which the preferred direction ofthe least wear lies in an octahedral plane. In the coordinate system X,Y, Z, the naturally occurring octahedral area (11 l) is shown. Itintersects the axes X, Y, Z at the coordinate values 1, l and 1. Thevector [111] representing the (111) plane, i.e. the vector normal to the(111) plane,

is illustrated by the appropriately marked arrow. The direction of theangle bisector of the triangle 1, l, l lying in the coordinate system ismarked [1T2] and is the direction of highest abrasion resistance whenthe [111] vector points downwards, out of the edge 8.

When one considers the position of the carbon atoms at the /4, A, A typepositions, it is evident that the corresponding direction of highestabrasion resistance for the (lit plane is the 1 121 direction when the111' vector points upwards in FIGS. 1 and 2, into the diamond, from edge8.

In a corresponding illustration in FIG. 5c the second embodiment ofa'stylus according to the invention is shown in which the direction ofrelatively optimum abrasion resistance lies in the naturally presentcubic planes of the diamond crystal system. In the coordinate system X,Y, Z the plane lies parallel to the plane determined by the Y and Z axesand intersects the X axis at the coordinate value 1. The preferreddirection [011], which represents the direction of relatively optimumabrasion resistance in the cubic plane (100), lies within this plane.This preferred direction is at an angle of 45 with respect to theparallels to the Y and Z axes in the plane (100).

In FIG. 50' an analogous illustration for the dodecahedral area of thenatural diamond crystal is shown. The plane is designated for itintersects the X and Y axes at the coordinate values X l and Y l with Z0. Within this plane, the preferred direction of use for the presentinvention lies in the direction of the drawn arrow; this direction isidentified by the symbol [T10]. This direction is always parallel to theline between the axial points X I and Y l, where the plane (110)intersects the X and the Y axes.

FIGS. 6 to 8 show empirically determined diagrams for abrasionresistance (this is known to be a measure for the hardness), as afunction of the angle at which the abrading surface was movingrelatively across the diamond surface. The quantity worn off underunchanging external conditions is plotted, so that the minimumscorrespond to directions of maximum abrasion resistance.

FIG. 6a shows the conditions for the cubic (100) plane in therectangular coordinate system, while FIG. 6b shows it in polarcoordinates. In the polar coordinate illustration the (100) plane ofFIG. 5a is also indicated. The same is shown in FIGS. 7a and 7b for thedodecahedral plane (110) and in FIGS. 8a and 8b for the octahedral plane(111). The planes appear in the polar coordinate graphs.

It can clearly be seen in thediagrams of FIGS. 6 to 8 that the wear.resistance is greatest in certain directions and is still quite high intheir vicinity within a certain tolerance range. By selecting anappropriate cutting angle when the stylus is cut out of a raw diamond,it is possible to produce a stylus with optimum abrasion resistance.

Different hardness stages smallest and largest amount of surface wearcan be derived from the diagrams of FIGS. 6 to 8.

Hardness stage 1: cubic planes at 45, 135, 225,

315 (hardest direction of all). I

Hardness stage 2: dodecahedral planes at 180,

Hardness stage 3: octahedral planes at 30, 150,

Hardness stage 4: octahedral planes at 90, 210,

Hardness stage 5: cubic planes at 0, 90, 180, 270,

Hardness stage 6: dodecahedral planes at 90, 270

(softest direction of all).

The hardness stages 1 to 6 here do not have the meaning of a hardnessscale, but are rather arbitrarily selected terms for the orientations ofthe mentioned directions in which the thus identified hardness stagesoccur. As can be seen, the hardness decreases with increasing number.

As already mentioned above, the stylus of the type illustrated in FIGS.1 and 2 includes an elongated lower edge of wedge shape which engages inthe grooves of the signal carrier to be scanned. This lower edge is atan acute angle of approximately 3 to 10 either linearly or according toa fixed curve in the direction of movement, while the face 6 liesapproximately perpendicular to the carrier plane and to the direction ofmovement. The abruptly ending trailing portion of edge 8 is ofparticular importance for a pressure scanning stylus.

For the selection of the optimum cut, it is thus the abrasion resistanceof edge 8 in contact with the carrier as well as the stability of thesharp perpendicular edge 6 which are decisive.

A relatively optimum cut is obtained by cutting the stylus out of a rawcrystal in such a manner that the edge 8 contacting the signal carrierlies an octahedral plane of the type (111) with the [112] directionlying in the direction of the friction force exerted by the carrier onthe stylus, this within a tolerance range of about 115.

According to a variation, the out can also be so selected that the edge8 contacting the signal carrier lies in the diagonal of a cubic plane(e.g. the [011] direction of FIG. 50), again comprehending a tolerancerange of about i.

In the polar diagrams according to FIGS. 812 for the octahedral planeand FIG. 6b for the cubic area it can be seen that for the above-givenorientations the quantity worn off is least, i.e. the abrasionresistance is highest.

A further usable variation of the cut consists in having the edge 8 ofthe stylus again under comprehension of a tolerance of about 115 lie onthe center line which connects the shorter sides of the rectangle of adodecahedral plane, e.g. the [T10] direction of FIG. 5d.

FIGS. 9-11 show these orientations, for example, in conjunction withschematically illustrated styluses. According to FIG. 9, stylus K is cutout of the raw crystal in such a manner that, as can be seen, theportion of stylus K contacting the signal carrier lies on an octahedralplane and, as indicated by the arrow marked hardness 3 with anorientation in the scanning direction or friction force direction. Thecubic plane is then inclined thereagainst at an angle of 55. The edgestability is here very good.

With a selection of the out according to FIG. 10, the stylus K whichcontacts the signal carrier lies in the diagonal of a cubic plane. Theabrasion resistance is here better than in the arrangement according toFIG. 9 (hardness l in FIG. 10), however the sensitivity regarding edgewear is greater since the octahedral plane which is inclined against thecubic plane by 55 only has hardness 3 as compared to the cubic planewith hardness 1 according to FIG. 9. For a cut according to FIG. 11 theedge contacting the signal carrier lies in the center line whichconnects the shorter sides of the rectangle of the dodecahedral plane.The cubic plane, however, is inclined by 45. The wear resistance is verygood with sufficient edge stability.

Since the frictional force in FIGS. 1 and 2 is more generally in thedirection of the horizontal of the undeflected disc record, it ispreferred as brought out in the General Aspects ofthe Invention toaccount for this by having the elongated lower edge 8 tilted downwardlyfrom the wear resistant plane and direction by an amount equal to theinclination of the edge, this lying between 3 and 10 as shown in FIG. 2,the vertex of the tilting lying in the leading portion 10. Thus, thewear resistant direction is that of horizontal arrow A in FIG. 2 and thewear resistant plane is perpendicular to the plane of FIG. 2.

It will be understood that the above description of the presentinvention is susceptible to various modifications, changes andadaptations, and the same are intended to be comprehended with themeaning and range of equivalents of the appended claims.

We claim:

1. A pressure scanning diamond stylus having an elongated lower edge ina wear resistant crystallographic orientation, said edge lyingsubstantially, with a tolerance range of about :t 15, in acrystallographic octahedral plane of the type (1 Lland extendingparallel to a direction of the type [112], the vector [111] pointing outof said edge, the direction [T12] extending from a leading portion ofsaid edge toward an abruptlyending trailing portion.

2. A pressure scanning diamond stylus having an elongated lower edge ina wear resistant crystallographic orientation, said edge lyingsubstantially, with a tolerance range of about il5, in acrystallographic cubic plane of the type and extending parallel to adirection of the type [011].

3. A pressure scanning diamond stylus having an elongated lower edge ina wear resistant crystallographic orientation, said edge lyingsubstantially, with a tolerance range of about :15", in a dodecahedralplane of the type (11 and extending parallel to a direction of the type[110].

4. A stylus as claimed in claim 1, said edge lying vertically tilteddownwardly from the recited orientation by an angle of about 3 towhose'vertex lies at a leading portion of said edge.

5. A stylus as claimed in claim 2, said edge lying vertically tilteddownwardly from the recited orientation by an angle of about 3 to 10whose vertex lies at a leading portion of said edge.

6. A stylus as claimed in claim 3, said edge lying vertically tilteddownwardly from the recited orientation by an angle of about 3 to 10whose vertex lies at a leading portion of said edge.

7. A method of using a diamond stylus at least for guiding a pickup in agroove on a record, the groove containing information-storing, physicalundulations of method comprising moving the stylus relative to therecord in the groove, whereby a friction force is exerted on thestylus'by the record, and orienting the stylus l) with a facesubstantially vertical with respect to the record for creating suddenlosses of contact between the stylus and the undulations and 2) with thedirection of the friction force lying substantially, with a tolerancerange of about :15", in a crystallographic octahedral plane of the type(111) and extending parallel to a di' rection of the type [T12], thevector [111] pointing out of the stylus and into the record, thedirection [112] extending in the same direction as said friction force.

8. A method of using a diamond stylus at least for guiding a pickup in agroove on a record, the groove containing information-storing, physicalundulations of a broad-band signal frequency mix, the stylus beingrounded for contacting both walls of the groove, the

' method comprising moving the stylus relative to the reof the type andextending parallel to a direction of the type [011].

9. A method of using a diamond stylus at least for guiding a pickup in agroove on a record, the groove containing information-storing, physicalundulations of a broad-band signal frequency mix, the stylus beingrounded for contacting both walls of the groove, the method comprisingmoving the stylus relative to the record in ,the groove, whereby afriction force is exerted on the stylus by the record, and orienting thestylus l) with a face substantially vertical with respect to the recordfor creating sudden losses of contact between the stylus and theundulations and (2) with the direction of the friction force lyingsubstantially, with a tolerance range of about 115, in a dodecahedralplane of the type and extending parallel to a direction of the type T1010. A method as claimed in claim 7, said stylus having a lower edgelying vertically tilted downwardly from the direction of the frictionforce by an angle of about 3 to l0 whose vertex lies at a leadingportion of the stylus.

11. A method as claimed in claim 8, said stylus having a lower edgelying vertically tilted downwardly from the direction of the frictionforce by an angle of about 3 to 10 whose vertex lies at a leadingportion of the stylus.

12. A method as claimed in claim 9, said stylus having a lower edgelying vertically tilted downwardly from the direction of the frictionforce by an angle of about 3 to 10 whose vertex lies at a leadingportion of the stylus.

13. A method as claimed in claim 7, said pickup being adapted forpressure scanning, the physical undulations providing signaloscillations in the megacycles/- second range. 14. A method as claimedin claim 8, said pickup being adapted for pressure scanning, thephysical undulations providing signal oscillations in the megacycles/-second range. I

15. A method as claimed in claim 9, said pickup being adapted forpressure scanning, the physical undulations providing signaloscillations in the megacyclesI- second range.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,781,020 Dated December 25th, 1973 It is certified that error appearsin the above-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 1, line 36 change "macroscopically" to I macroscopically--.

Column 6, line 55, after "extending" insert substantially, with atolerance of about 115 line 64 after "extending" insert --substantially,with a tolerance of about il5,--.

Column 7, line 3, after "extending" insert -substantially, with atolerance of about i-l5,-; line 30, after "extending" insert-substantially, with a tolerance of about i -l5,.

Column 8, line 1, after "extending" insert substantially, with atolerance of about i -l5,-; line 16, after "extending" insertsubstantially, with a tolerance of about i-l5,--; line 36, change"megacycles/." to -megacycles/; line 40, change "mega'cycles/." to-megacycles/; line 44, change "megacycles/. to -megacycles/----.

Signed aha sealed this 4th day of February 1975.

(SEAL) Attest:

McCOY n. (mason JR. 0. MARSHALL DANN" Attesting Officer Commissioner ofPatents

1. A pressure scanning diamond stylus having an elongated lower edge ina wear resistant crystallographic orientation, said edge lyingsubstantially, with a tolerance range of about + OR 15*, in acrystallographic octahedral plane of the type (111) and extendingparallel to a direction of the type (112), the vector (111) pointing outof said edge, the direction (112) extending from a leading portion ofsaid edge toward an abruptly-ending trailing portion.
 2. A pressurescanning diamond stylus having an elongated lower edge in a wearresistant crystallographic orientation, said edge lying substantially,with a tolerance range of about + or - 15*, in a crystallographic cubicplane of the type (100) and extending parallel to a direction of thetype (011).
 3. A pressure scanning diamond stylus having an elongatedlower edge in a wear resistant crystallographic orientation, said edgelying substantially, with a tolerance range of about + or - 15*, in adodecahedral plane of the type (110) and extending parallel to adirection of the type (110).
 4. A stylus as claimed in claim 1, saidedge lying vertically tilted downwardly from the recited orientation byan angle of about 3* to 10* whose vertex lies at a leading portion ofsaid edge.
 5. A stylus as claimed in claim 2, said edge lying verticallytilted downwardly from the recited orientation by an angle of about 3*to 10* whose vertex lies at a leading portion of said edge.
 6. A stylusas claimed in claim 3, said edge lying vertically tilted downwardly fromthe recited orientation by an angle of about 3* to 10* whose vertex liesat a leading portion of said edge.
 7. A method of using a diamond stylusat least for guiding a pickup in a groove on a record, the groovecontaining information-storing, physical undulations of a broad-bandsignal frequency mix, the stylus being rounded for contacting both wallsof the groove, the method comprising moving the stylus relative to therecord in the groove, whereby a friction force is exerted on the stylusby the record, and orienting the stylus 1) with a face substantiallyvertical with respect to the record for creating sudden losses ofcontact between the stylus and the undulations and 2) with the directionof the friction force lying substantially, with a tolerance range ofabout + or - 15*, in a crystallographic octahedral plane of the type(111) and extending parallel to a direction of the type (112), thevector (111) pointing out of the stylus and into the record, thedirection (112) extending in the same direction as said friction force.8. A method of using a diamond stylus at least for guiding a pickup in agroove on a record, the groove containing information-storing, physicalundulations of a broad-band signal frequency mix, the stylus beingrounded for contacting both walls of the grOove, the method comprisingmoving the stylus relative to the record in the groove, whereby afriction force is exerted on the stylus by the record, and orienting thestylus 1) with a face substantially vertical with respect to the recordfor creating sudden losses of contact between the stylus and theundulations and 2) with the direction of the friction force lyingsubstantially, with a tolerance range of about + or - 15*, in acrystallographic cubic plane of the type (100) and extending parallel toa direction of the type (011).
 9. A method of using a diamond stylus atleast for guiding a pickup in a groove on a record, the groovecontaining information-storing, physical undulations of a broad-bandsignal frequency mix, the stylus being rounded for contacting both wallsof the groove, the method comprising moving the stylus relative to therecord in the groove, whereby a friction force is exerted on the stylusby the record, and orienting the stylus (1) with a face substantiallyvertical with respect to the record for creating sudden losses ofcontact between the stylus and the undulations and (2) with thedirection of the friction force lying substantially, with a tolerancerange of about + or - 15*, in a dodecahedral plane of the type (110) andextending parallel to a direction of the type (110).
 10. A method asclaimed in claim 7, said stylus having a lower edge lying verticallytilted downwardly from the direction of the friction force by an angleof about 3* to 10* whose vertex lies at a leading portion of the stylus.11. A method as claimed in claim 8, said stylus having a lower edgelying vertically tilted downwardly from the direction of the frictionforce by an angle of about 3* to 10* whose vertex lies at a leadingportion of the stylus.
 12. A method as claimed in claim 9, said stylushaving a lower edge lying vertically tilted downwardly from thedirection of the friction force by an angle of about 3* to 10* whosevertex lies at a leading portion of the stylus.
 13. A method as claimedin claim 7, said pickup being adapted for pressure scanning, thephysical undulations providing signal oscillations in themegacycles/second range.
 14. A method as claimed in claim 8, said pickupbeing adapted for pressure scanning, the physical undulations providingsignal oscillations in the megacycles/second range.
 15. A method asclaimed in claim 9, said pickup being adapted for pressure scanning, thephysical undulations providing signal oscillations in themegacycles/second range.